As with other Bench areas, the Niagara Escarpment rises above this appellation along its southern boundary and protects it from the prevailing southwesterly winds. The several streams that flow through the appellation have eroded its rolling topography, and the land is marked by a complex array of slopes, steep V-shaped valleys, and a series of well-developed terraces. In the spring, when snowmelt and rainfall flood the riverbeds, the sloping bench provides good surface and ground water drainage, and feed abundant and picturesque waterfalls, notably Balls Falls. In the west, the north-facing slopes tend to be shorter and steeper, providing excellent air drainage.
With its relatively high elevation, and double bench formation, Twenty Mile Bench provides enjoys long periods of sun exposure during the summer and fall. Lake breezes pushing up against the Escarpment, circulate the warm air and extend warm daytime temperatures into the evening, encouraging and even and continuous ripening process.
The soils, laid down by passing glaciers are deep clay and till, with a high proportion of limestone and shale and quite a bit of variation in texture. These soils tend to be moderately well drained, and their density and water-holding capacities provide a definite advantage during the warmer period of the growing season when precipitation is limited and streams begin to dry up. Throughout the growing season, this soil moisture content promotes vine growth and balances the stress on mature vines.
A combination of short slopes of moderate steepness, high elevation and lake breeze circulations moderate temperatures and ensure gradual warming in the spring and gradual cooling in the fall. This also keeps day and night temperatures in a relatively small range during the growing season. The long even season offers good conditions for grapes to reach their full potential. Winter snow and spring showers ensure that the deep soils in the area are saturated at the start of the growing season, and moderate levels of precipitation supplement the growing season.
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VQA Ontario (2009)